Error in select

Question

Hi, below is my select, it returns an error: ORA-00904: "UNION"."QTD_ITEM": invalid identifier
SELECT
union.cod_company,
union.num_order,
union.cod_prod,
Sum(union.qtd_item) -- here is the error
FROM
SELECT
cod_company,
num_order,
cod_prod,
qtd_item_answ
FROM
ped_itens
WHERE
cod_company = '10' AND num_order = 798
UNION ALL
SELECT
cod_company,
num_order,
cod_prod,
(qtd_item)*-1
FROM
nf_item
WHERE
num_order = 798 AND cod_company = '10'
union
GROUP BY
union.cod_company,
union.num_order,
union.cod_prod
What's wrong?

Answer 1

qtd_item_answ is what you've called your column in the inner select.
As a side note, UNION is a reserved word, likely best to change your alias.